One of the first things a photographer learns about image formats is that JPEG image compression is “lossy”, meaning that the smaller file produced by greater compression comes at the cost of lower image quality. How much lower — whether low enough to “matter” — depends on the situation. JPEG compression can be remarkably effective at reducing the size of the image, so despite the lowering costs of storage space and bandwidth, the reduced size is still very appealing: storing essentially the same image in one fifth the file size, for example, means uploading five times faster.